Internally reactive structural joinder system

ABSTRACT

An internally reactive system for attaching one of its elements to another at a predetermined torque and axial tensile pre-load. The system includes a driver element, a fastener element, a workpiece element, and an interlinking element for interlinking the driver element and the workpiece element. The driver element constitutes a wrench with a driving arm, and a pressure-regulated fluid motor which turns the arm. The fluid motor exerts a force limited by the pressure of its motive fluid, and this force is directly proportional to the resulting torque level, because the system has no portion which during driving accelerates independently of any other portion, and no portion which overruns or impacts any other portion. The interlinking means may be a washer engaged by the frame of the driver element, and restrained relative to the workpiece element.

llnited States Patent 1 Wing 1 1 Mar. 1,1975

[ INTERNAILLY REACTKVE STRUCTURAL .lOlNlDER SYSTEM [76] Inventor: GeorgeS. Wing, 605 Paseo del Mar,

Palos Verdes Estates, Calif. 90274 [22] Filed: Apr. 3, 1973 [21] Appl.No.: 347,580

Related U.S. Application Data [62] Division of Ser. No. 179,799, Sept.13, 1971, Pat.

[52] U.S. C1 8l/52.4 R, 81/55, 8l/57.39

[51] int. Cl. 1325b B25b 13/46 [58] Field of Search 81/55, 56, 57.39,57.11, 81/57.l3, 57.14, 52.4 R

[56] References Cited UNITED STATES PATENTS 1,389,468 8/1921 White 81/551,812,816 6/1931 Weaver 81/57.4 X

2,005,348 6/1935 Michell 2,106,984 2/1938 Michell 2,961,904 11/1960Sergan 81/57 39 X 3,633,446 11/1972 Kawasaki et al.....

3,678,917 7/1972 Bender et al.

3,719,112 3/1973 Kaelon 81/57 39 Primary Examiner-James L. Jones, Jr.Attorney, Agent, or FirmDonald D. Mon

[57] ABSTRACT An internally reactive system for attaching one of itselements to another at a predetermined torque and axial tensilepre-load. The system includes a driver element, a fastener element, aworkpiece element,

and an interlinkine element forinterlinking the driver element and theworkpiece element. The driver ele ment constitutes a wrench with adriving arm, and a pressure-regulated fluid motor whichturns the arm.Thgilujd motor exertsa force limited by the pressure of its motivefluid, and this force is dlrectly propo r tional to the resulting torquelevel, because the system has no portion which during drivingaccelerates independently of any other portion, and no portion whichoverruns or impacts any other portion. The

, interlinking means may be a washer engaged by the frame of the driverelement, and restrained relative tg the workpiece element.

2 Claims, 14 Drawing Figures PHTENIEDMAR 4|975 3.868.872

sum 1 OF 4 FATENTED 41975.

SHEU 2 BF 4 wwm INTERNALLY REACTIVE STRUCTURAL JOINDER SYSTEM This is adivision of application Ser. No. 179,799, filed Sept. l3, 1971, now U.S.Pat. No. 3,759,l 19, issued Sept. 18, 1973.

This invention relates to fastener systems, to joinders provided bythem, and to elements of such a system.

The combination of a threaded nut and bolt is one of the most commonfastener systems. All parts of this system have been intensivelyinvestigated, commented on, improved and standardized, with theobjective of providing a reliable means for joining together a pluralityof objects. Over the years, as joinder requirements have become morerigorous, the state of the art as to threaded fasteners has beensteadily advanced. There is relatively little latitude for changes inbasic thread shapes and in fit-of-the-fastener concepts, so it is notsurprising that recent thrusts toward fastener improvement have been inthe direction of improving the fasteners reaction in the total system,and in tools and peripheral concepts for taking advantage of theinherent advantages of threaded fasteners.

Especially in joints which are subjected to relatively large loads, andto cycling loads, the installation of the fastener can make a vitaldifference in the reliability, strength, and life of the joint, and ofthe assembly which it holds together. Common examples are related to theresistance of a joint to fatigue failure. Three examples of areas inwhich advances have been sought are: (a) good surface finish, whichreduces points of stress concentration; (b) interference fits of thebolt in the wall of the workpiece, which radially compresses thematerial of the workpiece at the wall of the hole so as to isolate it atthat point from cyclical forces up to a predetermined level; and (c)general tightness of the joint which prevents slack movements in thejoint with attendant high shock loads. In each case, substantialimprovements have in fact been made. The ultimately desired result isevident a joint which is as strong as the workpiece, and which does notby its own presence create new problems. Threaded joints can involveproblems in each of these areas.

Of the examples given above, the general tightness is the one which issubject to greatestvariation in the course of actual installation, andat the same time has one of the greatest effects on the strength andlongevity of the joint. The tightness is, in turn, related to the axialclamping force exerted by the fastener. When a nut is tightened onto abolt, the bolt is stretched, and its relaxation force is a clamping one.This is called axial pre-load, and its uniform attainment results bothin a reliable fastener, and in a joint comprised of many identicalfasteners, of a more reliable joint.

The ideal means for measuring pre-load is by measuring the actualstretch of the bolt. However, means for doing this quickly andaccurately in production do not exist. Therefore, the only useful andcontrollable pa rameter is the torque applied to the collar (nut)relative to the pin (bolt). At least in theory, the torque applied willbe proportional to the axial pre-load on the fastener, because when thecollar is tightened down and bears against an adjacent washer or face ofa workpiece, the thread reaction stretches the bolt. The tensile forceexerted by the stretched bolt is the axial tensile preload. This loadholds the joint tightly clamped together, and the torque level used iscommonly selected to produce a desired axial pre-load, on the assumptionthat the two are directly proportional. However, in practice, thisdirect proportionality can be adversely affected by several importantvariables. i

Especially in critical installations, the attainment of the designobjective for each joinder, and repetitiveness of effect from joinder tojoinder are critical considerations. in theory, and to a significantextend in tually exerted becomes uncertain. Torque wrenches formeasuring the torque involve calibration problems, and exertion ofstrong forces, or forces quickly applied, involve the risk of excessiveor peak loads which may apply excessive torques. Excessive torque canconstitute a severe risk, because the threads may be stripped, andbecause the fastener may be pre-loaded to too great a percentage of itscapacity.

These problems have been treated in various ways. In one system, asexemplified by George S. Wing U.S. Pat. No. 2,940,495, entitled Lock Nutwith Frangible Driving Portion, torque limitation is made inherent inthe collar by providing a shear section which shears at a design torque,and causes the driving surfaces to separate from the threaded body ofthe collar at the desired torque level. This system has enjoyedwidespread acceptance. However, when large-diameter fasteners areinvolved, such as for one inch and greater diameter bolt threads, themanufacture of the driving section to suitable tolerances makes thefastener more expensive than one would wish. Also, when the shearsection fractures, the release of the driving surfaces causes amechanical shock to be exerted on the installer, which many installersobject to.

To overcome this latter disadvantage in setting an inherentlytorque-limited fastener, the wrench shown in U.S. Pat. No. 3,247,741,issued Apr. 26, 1966, to R. W. Batten, entitled Machine Wrench withTorque Reaction Means, was invented. in this wrench the frame is engagedto a washer, which washer is restrained relative to the pin. The frameis also restrained to the pin. Then when fracture occurs, the releaseoccurs exclusively within the tool, and is not felt by the installer.This system constitutes a very substantial advantage in the applicationof larger sizes of inherently torquelimited fasteners. It does not,however, suggest or provide means for setting a driver to a given torqueand axial pre-load level when no inherent limitation is provided in' thefastener itself.

The Battenwrench does suggest a solution to one problem of settingfasteners to a given level, and that is by the divorcement from theapplied torque level of the degree of restraint on the handle of thewrench. It is evident that the torque on the wrench must be equal andopposite to that which is applied to the fastener, and that if thesupport on the frame yields, then the torque level will change. Apartfrom the class of driver exemplified by the Batten device, the appliedtorque is very difficult to control, and even. in the Batten device,where the wrench handles reaction with its surround- 3 ings is renderedunimportant, no means is provided for determining the exact torque whichis exerted by the wrench, because that level is unimportant so long asthe torque applied exceeds the level at which the inherent limitation inthe collar functions, i.e., the shear section fractures.

Still another problem in the prior art relates to the rate ofapplication of force to the fastener by the wrench. Various impact andoverride type wrenches are known which approximate the applied torque bythe application of a blow by a hammer of known weight against an anvil,or which slip a clutch as a function of a frictional grip ona drivingsocket. In these devices the velocities or accelerations of the drivingmeans are permitted to exceed those of the object being driven, andaccordingly, a peak load can be exerted by a blow, or by sudden stoppageof the collar. In either event, a force other than the design force maybe exerted, thereby setting the fastener to an unknown torque, or atleast to one other than its design level. The usage of such devicesrequires the consideration of many variables, such as the tightness ofthe joint, relative surface finishes, and the like, all of which arethemselves subject to variation from joint to joint.

It is an object of this invention to'provide an internally reactivestructural joinder system wherein a fastener elementmay be set in aworkpiece element by a driver element acting through an interlinkingelement so that the operators skill and judgment can be ignored as tothe accuracy of the joinder, and in which a fastener element, which neednot include inherent torque limitation means, can be set to precise,adjustable, and repeatable torque and axial pre-load levels.

It is also an object of this invention to provide a torque wrench whichis useful with fastener elements other than those of this system, andwith which, provided the wrench frame is properly restrained, the saidfastener elements can be set accurately and quickly to predeterminedtorque and axial pre-load levels. The levels can readily be selected bya simple adjustment of a pressure regulator. Large forces can be exertedby the wrench itself so that large fasteners may be set to high torques.

It is another object of this invention to provide a fastener element foruse in a system of this type wherein the inherent resistance of thecollar to being tightened onto the pin is standardized, and adeleterious effect on the first few thread convolutions of the collarwhich often occurs in conventional installations is greatly minimized.

The system of this invention is provided for the purpose of attachingone of its elements to another of its elements. It includes a driverelement, a fastener element, a workpiece element, and an interlinkingelement for interlinking the driver element and the workpiece element.The driver element constitutes a wrench with a driver arm and a fluidmotor which turns the arm. The fluid motor exerts a force limited by thepressure of its motive fluid. The torque exerted in the system isdirectly related to this pressure, because the system has no portionwhich accelerates independently of any other portion, and no portionwhich overruns or impacts any other portion.

According to a preferred but optional feature of this invention, thefluid motor is a linear actuator; for example, a piston-cylindercombination.

According to still another preferred but optional feature of thisinvention, an adjustable pressure regulator regulates the fluid pressureand thereby the applied torque.

The above and other features of this invention will be fully understoodfrom the following detailed description and the accompanying drawings,in which:

FIG. 1 is a perspective view of the presently preferred embodiment ofthe invention;

FIG. 2 is a top view of FIG. 1, partially in schematic and partially incutaway notation;

FIGS. 3, 4, and 6 are cross-sections taken at lines 3-3, 4-4, 55 and6-6, respectively, of FIG. 2;

FIG. 7 is a cross-section showing another embodiment of the invention;

FIG. 8 is a cross-section taken at line 88 of FIG. 7;

FIG. 9 is a cross-section showing still another embodiment of theinvention;

FIG. 10 is a cross-section taken at line 10-10 of FIG. 9;

FIG. 1 1 is a cross-section of still another embodiment of theinvention;

FIG. 12 is a cross-section showing a preferred embodiment of a portionof the invention; and

FIGS. 13 and 14 are cross-sections taken at lines 13-l3 and 14-14,respectively, of FIG. 12.

The system according to the invention is best shown in FIG. 6 andincludes a driver element 20, a workpiece element 21, a fastener element22 and an interlinking element 23. It is a function of this system toset the fas tener element to the workpiece element at a predeterminedtorque and axial pre-load.

Workpiece element 21 comprises bodies 25 and 26 of material such asaluminum, stainless steel or the like and preferably will be entirelymetallic. The workpiece element is shown comprising bodies 25 and 26which schematically represent a plurality of objects to be held togetherby the fastener element.

An aperture 27 is formed through the workpiece element with acylindrical inner wall 28 having a reference diameter. It has a firstsurface 29 and a second surface 30 which preferably but notnecessarilyare parallel to each other.

The fastener element 22 comprises a pin 34 with an elongated shank 35having a cylindrical outer wall 36 adapted to be fitted in the wall ofaperture 27. This outer wall frequently will have a larger diameter thanthe reference diameter for the purpose of making an interference fit inthe hole, although this is not essential to the practice of theinvention.

A head 37 is formed at one end of the shank to bear against the firstsurface of the workpiece. This is an example of a means for restrainingthe shank from axial removal from the workpiece. The aperture and theshank share a common central axis 38. An external thread 39 is formed onthe pin 34 at the end opposite the head and projects from the aperturebeyond the first said surface.

The said fastener also includes a collar 40 which is annular and has acentral passage 41 therethrough with an internal thread 42 adapted toengage and be tightened onto external thread 39.

The collar includes a bearing face 43 surrounding the end of the passagecloser to the workpiece. A plurality of blades 44 project beyond theouter periphery of the nut for an engagement by a drive socket yet to bedescribed. It will be seen that the fastener clement thereby comprisespin 34 and collar 40 which are adapted to be used as a nut and bolt. I

lnterlinking element 23 comprises in the preferred embodiments as shownin FIGS. 6 and 12-14, an annular body 45 in the form of a washer havinga first bearing face 46 abutting the first surface 29 of the workpieceand a second bearing face 47 in abutment with bearing face 43 on thecollar. It carries a plurality of blades 48 on its periphery forengagement by a driver element yet to be described.

The driver element is shown in detail in FIGS. 1-6. It is an assemblycomprised of a motor section 50, a transmission section 51 and a wrenchsection 52. It is held together by appropriate assembly means and isprovided with a pair of handles 53,54 so that it may conveniently beheld by the installer.

A control knob 55 for an adjustable pressure regulator valve, which willlater be described, is provided at the top surface of the driverelement, together with a gage 56 which will indicate the regulatedpressure, preferably in numerals calibrated as to torque.

A clutch selector 57 providing a pair of buttons 58, 59 for theinstaller is also included at a readily accessible location. A dragadjustment means 60 is also accessible to the user. Fastener element 22is shown at the bottom end of the wrench section. These sections andtheir component parts will now be described in greater detail withinitial reference to FIG. 2.

A frame 61 which comprises the assembled structure of the varioussections serves to house the various portions of the invention. In orderto apply power thereto, there is a pressure supply port 62 adapted to becon nected to any desired fluid under pressure, which fluid may becompressed air, pressurized hydraulic fluid, or whatever is preferredfor the use at hand and the pressures to be utilized. The pressuresupply portfeeds pressure to a pressure conduit (sometimes calledpressure conduit means) 63. In the pressure conduit there is provided apressure regulator valve 64 which is adjustable by turning control knob55. This is a relievingtype regulator valve of conventional design anddischarges gas into the downstream portion 65 of the pressure conduitand maintains it therein at the adjusted pressure. Gauge 56 is connectedto portion 65 by branch 66.

Pressure is fed to a trigger valve 70, which trigger valve includes abutton 71 adjacent to handle 54. The button is carried by an axiallyshiftable valve spool 72, which is spring-loaded by spring 73 to avented position, with the button biased away from the frame. The valvespool is slidingly fitted in bore 72a. A vent conduit 72b open to theatmosphere also opens into the wall of the bore. Portion 65 of thepressure conduit and conduit 77 similarly open into the said wall. Aslot 74 is formed in he wall of the spool, and extends for such a lengththat it overlaps conduits 72b and 77 when the trigger is released so asto vent conduit 77, and to overlap conduits 65 and 77 when the triggeris depressed so as to connect conduit 77 to the pressure source tooperate the wrench. O-rings 75 are provided as necessary to preventleakage of fluid under pressure.

The venting of conduit 77 unlocks the wrench when power is off so itsdrive mechanism can be manually moved without impediment from fluidtrapped in conduit 77 and the motor downstream from it.

Conduit 77 connects to a direction selector valve 78 (sometimes calleddirection selector valve means).

This direction selector valve is shown only schematically in FIG. 2 andis shown in full detail in FIG. 5. It is the function of the directionselector valve to determine the direction of supply of pressure andexhaust fluid to and from a fluid motor 80 (best shown in FIG. 2). Itdoes so through pressure supply conduits 81, 82, which extend topressure supply ports 83, 84 of the fluid motor, respectively. Conduit77 opens medially in a valving surface 85, and conduits 81, 82 open intosaid surface on opposite sides thereof. A valving chamber 89 faces saidvalving surface. Valving surface is planar. Exhaust ports 90, 91 extendfrom the valving chamber to atmosphere or to reservoir as the case maybe, and constitute exhaust conduit means.

The direction selector valve 78 comprises a slide valve utilizing saidvalving chamber and a slider 92, which slider has a pair of arms 93, 94and which are'axially spaced apart from each other and which slide influid sealing contact along the valving surface. It will be seen that inall axial positions of the slider, the arms will span the entry point ofconduit 77 and may selectively also bridge one or the other of supplyconduits 81, 82. Exhaust ports 90 and 91 are always open to exhaust.They will, however, be connected only to that one of conduits 81, 82which is not at the time connected to the supply pressure. This devicethereby constitutes a four-way valve, providing for a selectiblebi-directional flow of fluid through conduits 81, 82 as indicated byarrows 95, 96. It therefore follows that the axial position of theslider will determine which of conduits 81, 82 is under pressure andwhich is under exhaust conditions at any given time.

The slider is provided with a tang 97, which is springloaded by spring98 to press the arms 93 and 94 firmly against valving surface 85 andalso to provide for axial reciprocation of the slider. Thisreciprocation is accomplished with a shuttle valve which includes acylinder 101 within which there is fitted a cylindrical shuttle 102having a cavity to receive the tang so that, when the shuttle shiftsaxially in its cylinder, it will take the slider with it. A relief 103is provided to pass the tang through the wall of the cylinder 101.

A pair of shuttle passages 104, 1.05 open into respective chamber 101aand 101b at the opposite ends of cylinder 101. Passages 104 and 105proceed to connect to branches respective 106, 107 which are connectedto conduit 77 of the pressure conduit 63. They are also connected topilot valves 108, 109 (see FIG. 2). Cylinder 101 is bored into the bodyof the mechanism and is closed by a plug 110. The pilot valves 108 and109 are identical to one another so that only pilot valve 108 will bedescribed in detail. It includes a bore (see FIG. 4) in body 116 inwhich a pair of inserts 117, 118 are placed. The-inserts are providedwith appropriate O-ring seals 119, 120 and 121. An axially shiftablevalve stem 122 projects from the body and carries inside the body aperipheral seal 123 which is adapted to close a seat 124 to isolateshuttle passage 104 from vent passage 125. A bias spring 126 bearsagainst a spring retainer 127 which is held in place by a snap ring 128to bias this valve to a closed position. The strength of this spring issufficient to withstand the force of the pressure in conduit 104. Whenthis valve is closed as shown in FIG. 4, fluid is trapped in shuttlepassage 104 and when it is open the shuttle passage is vented to theatmosphere or to such reservoir as might be provided in view of theclass of working fluid being used. Pilot valves 108 and 109 aresometimes referred to as pilot means, and constitute examples of meanswhich are co'ntactible by the lever arm and are operatively connected tothe direction selector valve means 78 to set means 78, and thereby todetermine the direction of operation of fluid motor 80. In the examplegiven, the operative connection to the direction selector valve means isby means of shuttle valve 100. The shuttle 102 is pressure balanced inthe sense that it will not assume any particular position when theforces in chambers 101a and llb are equal, but moves only in response toa difference of pressure in these two chambers.

The motor section includes the bi-directional fluid motor which operatesbi-directionally along axis of actuator 130. In the presently preferredembodiment of the invention as shown in FIG. 2, the motor is a linearactuator and a piston-cylinder variety. A cylinder 131 is provided inwhich a piston 132 is axially slidable. The piston is conventional, andmakes a sliding fluid sealing fit in the cylinder by means of a'pistonring 133. Supply ports 83 and 84 enter the cylinder on opposite sides ofthe piston so that neither is ever covered by the piston and they arealways separated by it.

Two bumpers 134, 135 act as a safety limit means to limit the excursionof the piston.

A sliding seal 136 in the nature of a packing is provided around shaft137 which shaft is attached to the piston by means of nut 138 thatpresses it against a shoulder 139 on the shaft. The shaft is slidablethrough the opening formed by the sliding seal 136 and extends to aknuckle joint 140 which joins the shaft to a link 141. The link is inturn pinned to a lever arm 145. The lever arm pivots around a wrenchingaxis 146 and swings in an are shown by arrow 147. This are willordinarily be on the order of 14 and this will cause it to move from alimiting position shown in FIG. 2 where it bears against valve stem 148of pilot valve 109 to its other limiting position where it bears againstvalve stem 122 of pilot valve 108. It will be seen from the foregoingthat when the trigger is depressed, the direction selector valve willcause motion of the motor in one or the other of its directions and whenit reaches the extent of that motion, pilot pin 149 which projects fromthe lever arm to contact the respective stems, will react with therespective pilot valve so as to shift the direction selector valve tothe opposite position, causing reversal of the fluid connections. Thesewill be described in more detail later but are given at this point tomake it plain that the lever arm will oscillate in the arc of the planeof FIG. 2 so as to operate the wrench section yet to be described.

The wrench section is bestshown in FIG. 6. The objective of the wrenchsection is to apply counterrotative force to set the fastener. Itincludes a frame 150 which makes a splined attachment 151 with an outertubular anchor means 152. When the driver element is not to be attachedto an interlinking element, then anchor means 152 may be eliminated.Blades 153 are provided to make an engagement with blades 48 on theinterlinking element. These blades are geometrically congruent with oneanother for this purpose.

' Inside the anchor means is provided a driver socket 154 which hasblades 155 in its inner end to engage blades 44 on the collar so as todrive the same, and blades 44 and 155 are geometrically congruent forthis purpose. Anchor means 152 is generally made nonrotative relative tothe frame, and driver socket 154 is rotated relative thereto. Aspring-loaded ball detent comprising a ball 156, a spring 157 and agroove 158 is provided for releasably retaining the drive socket axiallyon drive shaft 160. A dowel 152a is provided for retaining anchor meansto the drive socket. It is a cross pin seated in the frame. It permitsrotation of the drive socket, because the external groove on the drivesocket is fully peripheral, and the center part of the dowel merelyrides in it, while still retaining the drive socket axially. A splinedjoint 159 joins the drive socket to a drive shaft 160, which isrotatively mounted in the frame. Therefore, rotation of the drive shaftwill turn the drive socket in the respective direction of rotation.Lever arm 145 terminates at a rotatable drive ring 161, which has afirst and a second drive face 162, 163, respectively. These faces areprovided with teeth 164, which have driving faces facing in onedirection and ramp-releasing faces 166 facing in the other direction,whereby turning the arm in one direction will cause a driving actionthrough the driving faces, and reversal will cause a ratcheting-releaseaction over the releasing faces. The driving faces of the two drivefaces face in opposite directions so that, when one set is engaged,driving will occur in one direction for a given direction of movement ofthe lever arm, and the opposite takes place at the other face. Selectionis made by means of a pair of selector rings 167 168, which respectivelyface faces 163 and 162. These selector rings carry teeth which match theramp-releasing faces and driving faces of the drive surface to which itis opposed, and it will thereby be seen that selectively engaging aselector ring with its respective drive surface will cause respectivecorotation. This is accomplished by providing slide means for thispurpose such as shown in FIG. 3, where buttons 58 and 59 are shown onthe end of a shaft 170, which is joined to a yoke 171.

The yoke is adapted to bear against the two selector rings so as topermit one to be brought into bearing contact with a respective drivesurface and to move the other one out of contact. For this purpose,there is provided a pair of bias springs 172, 173, which bias therespective selector rings toward the drive ring. Respective branches174, of the yoke will be brought to bear against peripheral flanges 176,177 on the selector rings so as to press one away from the drive ringand permit the other spring to bring the other selector ring intocontact therewith. It will thereby be seen that shifting the shaft 170along its axis will enable one or the other of the selector rings tomake contact with the drive ring.

Transmission of the rotation to the drive shaft 160 is by means ofsplines 178, 179 for selector rings 167 and 168, respectively. In FIG.6, selector ring 168 is shown drivingly connected, and selector ring 167is shown disconnected, and it will be assumed that the driving faces andramp-releasing faces will face in the counterclockwise direction, andthe selector ring 167 will have no effect because it is not selected.Ball detent 180 (see FIG. 2) is provided to engage grooves 181, 182 inthe shaft 170 for holding the shaft in an adjusted selected position. Inevery case, the combination of one of the drive faces and a respectiveselector ring constitutes a unidirectional clutch means. In pairs, theyalso constitute a means for selecting the direction of driving rotation,which, in this case, may be selected for left or right hand rotation.

It is not desirable for the drive shaft to rotate completely freely, andtherefore, a small drag is provided. For this purpose, at the top of thedrive shaft there is provided a bearing 185, the inner race 186 of whichgives side support and axial support to the upper end of the drive shaft160. A nut 187 and nut retainer 188 are threaded to the top of the driveshaft and bear against a drag plate 189. This dragplate is borne againstby a deformable disc 190, such as a rubber disc, the pressure of whichagainst the drag plate is determined by the tightness of drag-ad-justingmeans 60, which is a threaded cap threaded into the end of the body. Itwill thereby be seen that the drag force between the drag plate and theupper end of the shaft will provide some small and adjustable dragopposing free rotation of the drive shaft.

Other means for obtaining the objectives of the invention utilizing theinterlinking means with the fastener means are shown in FIGS. 7-14,inclusive. In FIG. 7, workpiece 200 is shown with a pin 201 installed inan aperture 202 therein. A collar 203 is tightened thereon by anchormeans 152 and socket 154. The distinction between the device of FIG. 7and of FIG. 6 resides in the fact that the interlinking element 205 comprises a boss 206 formed as a part of the workpiece surrounding theaperture. It has blades 207 to engage the blades on anchor means 152.

FIGS. 9 and 10 show a restraint for an interlinking means 208 exerted bya direct physical abutment rather than by frictional contact. Theworkpiece 210 has an aperture 211 to pass a pin 212 therethrough. Acollar 213 is brought against a washer 214, which washer has a hexagonalouter boundary 215. A raised ring 216 formed on the workpiece surroundsthe aperture and has an internal hexagonal boundary 217, which restrainsthe washer against rotation. The wrench socket drives the collar. Theanchor means is restrained by the washer, and the washer is physicallyrestrained by ring 216 on the workpiece.

In FIG. 11 there is shown still another interlinking means 220. Pin 221is tightly held in aperture 222 in a workpiece 223 by virtue of a closefit therein. Splines 224 on the pin are engaged by splines 225 on awasher 226 to hold the washer against rotation, the washer being engagedby the anchor means.

The presently preferred embodiment of interlinking element and collar isshown in FIGS. 12-14 wherein on the threaded end of a pin 230 there isthreaded a collar 231, which collar has blades 232 to be engaged anddriven by the drive socket, and a bearing face 233 to engage theinterlinking element 234. The interlinking element is in the form of awasher which encircles and passes the pin and has first and secondbearing surfaces 235, 236 to be sandwiched between the bearing face ofthe collar and the surface of the adjacent workpiece. The interlinkingelement has blades 237 to be engaged by the anchor means. Of importanceto this embodiment of the invention is a tapered inner wall 238 thatdefines a central aperture in the interlinking element and a taperedouter wall 239 on the collar, which tapered walls are at least partiallyaxially coextensive when the device is installed, and they are alsoradially spaced apart from one another. It will thereby be seen that anose 240 is provided on the collar which is not subjected to radialpressures by the interlinking element, and this frees the first threefully formed convolutions 241 of the collar from the uncertainties andwhile it extends generally axially, its lateral dimensions relative tothe corresponding dimensions of the inner wall of the washer when thefastener element is fully installed, are less, thereby to provide theclearance (radial spacing) between the nose and the inner wall. Theillustrated tapered frustoconical walls illustrate this feature.

It is well known that the first. three fully formed thread convolutionsof a collar transfer a disproportionate percentage of the load from thepin, compared to the remaining threads. Accordingly, variables at thesethreads are to be avoided should a standardized joint be desired. Whenthe end of .a collar is brought to bear against a surface, and the firstthree fully formed threads are located directly adjacent to theinterface, distortion effects may occur which can change the interfaceconditions at the engaging surfaces of these threads. In the embodimentof FIGS. 12-14, these threads are in nose 240, in a region ahead of thedistortive forces, and radially spaced from the washer. Accordinglythese convolutions, which will still transfer a disproportionatelylarger share of the load, do so in a free and undistorted condition.

The operation of this system will now be described. First, theinterlinking element is selected and assembled with the fastener and thepin inserted in the aperture. Then the anchor means is applied to theinterlinking means and the drive socket to the collar. One or the otherof buttons 58 or 59 will have been pressed to determine the direction ofdriving rotation, clockwise or counter-clockwise. In the event that itis to be clockwise, the setting will have been made as illustrated inFIG. 6, whereby drive ring 161 and selector ring 168 are engaged fordriving rotation.

The trigger is pressed, and the spool is shifted so slot 74 overlaps andconnects conduits 65 and 77, and pressurized liquid at the adjustedpressure passes through the trigger valve and to the direction ofselector valve and shuttle valve. Assuming that the end of the lever armis between the two pilot valves, and that the shuttle will be on one orthe other ofits extreme positions, then fluid from conduit 77 will flowto a respective one of conduits 81 and 82 to one side or the other ofthe piston. Exhaust fluid will flow to the other of those back into thevalving chamber 89 and out the respective one of exhaust ports 90 or 91.This motion will continue and may initially be either a ratchetingrelease of the clutch, or a forward driving of the same. In eitherevent, when one or the other of the pilot valves is struck by the leverarm, it will be opened and will vent the pressure in its respective line104 or 105. This will then unbalance the shuttle 102 and will cause itto move in the direction of the released pressure because the other sidewill remain under full system pressure. This will carry the directionselector valve to its opposite position and will reverse thepressurization of the conduits 81 and 82. There will, therefore, followa continuous cycling operation of the motor so long as the trigger isheld down and so long as the torque resistance through the wrenchingportion of the device does not exceed the torque generated by the motor.

When the lever arm moves in the clockwise direction, the drive faces ofthe clutch means will cause rotation of the wrench, and when thereversal occurs by virtue of contact with pilot valve 108, then therewill be a ratcheting release. The opposite situation would be true werethe setting of the direction selector valve 78 opposite, and drivingwould occur in a counterclockwise direction.

The direction selector valve is simply a four-way valve for directingthe pressure to one of the sides of the piston at a given time, and theshuttle valve is for the purpose of resetting the selector valve as afunction of pilot valve operation.

It is plain that the torque exerted is a direct function of the pressureestablished by the pressure regulator 64 and that the force delivered isa function of the product of that pressure and the area of the piston.

Link 141 is provided to take out any slack and to minimize as far aspossible the small-angle error resulting from angular movement of thelever arm.

The motor will stall when the resistive torque from the fastener elementequals the torque exerted by the driver means. It is important to notethat at this time there is no over-running of the device. The motorsimply stalls, and this is an important distinction from prior arttorque limited drivers. Except for the very small unavoidable motion inthe re-engagement of the clutch in the driving action after a reversal,there is no overrunning of any part of this system, and even this may bereduced by utilizing a roller type clutch, or by increasing the numberof teeth on the clutch faces.

When the trigger is released, spring 73 returns the spool to theillustrated position, conduit 77 is cut off from pressurized fluid andvented, and motion stops.

It will now be seen that when the anchor means is utilized so as tocouple the system between the drive socket and the anchor means, theoperator is entirely removed from the torque setting operation and thata readily adjustable, completely accurate and reproducible torque isapplied to the fastener.

Similarly, this device provides a very accurate torque wrench which maybe utilized without the anchor means provided only that means isprovided for the restraining the frame against counter-rotated motionderived from the system.

The various embodiments of interlinking means are provided to illustratethe wide range of selections one has at his disposal with this systemfor achieving the objective of anchoring the driver element to theworkpiece element. In the preferred embodiment, the restraint isattained by the frictional drag between the abutting faces of theworkpiece and of the washer. The area of contact at this interface ispreferably greater than that between the collar and the washer in orderthat the greater force may be that which tends to restrain them.Although the washer is initially freely rotatable, as soon as the collaris lightly tightened the frictional force will prevent further rotationof the interlinking means and will provide a firm anchorage for theframe of the driver. Similar results are attained by provided bosses onthe surface of the workpiece or by anchoring the washer either by meansof the workpiece directly and mechanically as in FIGS. 9 and 10 orthrough the pin as shown in FIG. 11.

It is evident that the fluid motor may be a linear or a rotary typeactuator depending on the preference of the user or designer so long asa torque is applied at the end of a fixed lever arm as a consequence ofa fluid pressure applied to a resistive but movable surface. It is alsotrue that the axis of motion of the fluid motor need not be in a planenormal to the wrench axis as shown, but this will be found to be acompact and very versatile arrangement for a practical wrench.

This invention is not to be limited by the embodiments which are shownin the drawings and described in the description which are given by wayof example and not of limitation but only in accordance with the scopeof the appended claims.

I claim:

1. An internally reacting system for attaching one of its elements toanother of its elements at a predetermined torque level and with apredetermined level of axial tensile preload, said system comprising adriver element, a fastener element having an axis, a workpiece element,and an interlinking element for interlinking the driver element and theworkpiece element, said fastener element comprising a pin with acylindrical shank having a central axis, a peripheral thread on saidshank, and a collar including a peripheral flange, a peripheral bearingface on said peripheral flange, an axiallyextending nose projectingbeyond said bearing face bearing an outer wall, and an internal thread,said collar being adapted to be threaded and tightened onto theperipheral thread of the pin, said workpiece comprising a body having abounding surface and an aperture opening onto said bounding surface intowhich the shank fits, the peripheral thread projecting beyond saidbounding surface, the pin being restrained against axial removal fromthe workpiece in the direction of the peripheral thread, saidinterlinking element comprising a washer including engagement surfaces,a central aperture at least in part defined by an inner wall to encircleand to pass the pin, and bearing surfaces to abut against the collar andagainst the workpiece when clamped between them by tightening the collaronto the pin, and the washer being restrained against rotation relativeto the workpiece at least in part by frictional forces developed fromcompressive forces on the bearing surfaces, which forces are exerted onthe washer by the collar through the said peripheral bearing facedisposed on the said peripheral flange, the axially-projecting nose ofthe collar beingadapted to be inserted into the central aperture of thewasher, its outer wall having lateral dimensions such that when soinserted they are less than corresponding lateral dimensions of theinner wall, whereby the nose is radially spaced from the inner wall ofthe central aperture when the fastener element is fully assembled, atleast the first three completely formed thread convolutions of thecollar closest to the end of the nose most removed from the peripheralflanges lying axially within the nose, whereby to be located closer tothe workpiece than the bearing face on the collar, said driver elementcomprising a frame, engagement means on said frame to engage theengagement surfaces on the interlinking element and restrain the frameagainst rotation relative thereto, a wrench having a central axis ofrotation rotatably mounted to the frame and adapted to engage the collarto tighten it onto the peripheral thread, a lever arm attached to thewrench, projecting therefrom and adapted to be driven in an are aroundthe said central axis to turn the wrench, fluid motor means mounted tothe frame and connected to the lever arm at a distance from the centralaxis to cause said driving of the lever arm, a source ofpressure-regulated fluid, and valve means admitting lever arm ofpredetermined length, whereby the inter-' linking means restrains theframe against rotation while the wrench tightens the collar onto thepin, and the fluid motor means applies a regulated and substantiallyconstant force and the wrench thereby applies an accurately regulatedtorque, all independently of other restraints on the frame or on theworkpiece, the applied torque being determined and limited by theapplied fluid pressure, and there being no freedom of movement of anyportion of the driver element from the fastener element when they areengaged which would enable a differential velocity to exist.

2. An internally reacting system for attaching one of its elements toanother of its elements at a predetermined torque level and with apredetermined level of axial tensile pre-load, said system comprising adriver element, a fastener element, a workpiece element, and aninterlinking element for interlinking the driver element and theworkpiece element, said fastener element comprising a pin with acylindrical shank, a peripheral thread on said shank, and an internallythreaded collar adapted to be threaded and tightened onto the peripheralthread, said workpiece comprising a body having a bounding surface andan aperture opening onto said bounding surface into which the shankfits, the peripheral thread projecting beyond said bounding surface, thepin being restrained against axial removal from the workpiece in thedirection of the peripheral thread, said interlinking element comprisinga body with engage-ment surfaces, said body being adapted to berestrained against rotation relative to the workpiece, said driverelement comprising a frame, engagement means on said frame to engage theengagement surfaces on the interlinking element and restrain the frameagainst rotation relative thereto, a drive shaft mounted to said frameand rotatable therein around a central axis; a lever arm;unidirectionally driving clutch means engaging the lever arms to thedrive shaft for driving the drive shaft in one direction of lever motionand releasing it in the other direction; a bi-directional fluid motormounted to said frame and drivingly connected to said lever arm, saidfluid motor having a pair of supply ports; pressure conduit means;exhaust conduit means; an adjustable pressure regulator in said pressureconduit means maintaining pressure downstream therefrom at a constantand selected value; direction selector valve means in said pressureconduit downstream from said regulator; a pair of supply conduits connected to said direction selector valve means, one being connected toeach supply port of the fluid motor; pilot means contactible by thelever arm and operatively connected to said direction selector valvemeans for setting the same and thereby determining the direction ofoperation of the fluid motor, the fluid motor thereby cyclingbi-directionally and driving the lever arm back and forth and drivingthe drive shaft unidirectionally as a consequence of the alternateengagement and release of the clutch means, said valve means admittingfluid to the fluid motor under pressure so as to drive the same with apredetermined force against the lever arm, whereby the interlinkingmeans restrains the frame against rotation while the wrench tightens thecollar onto the pin, and the fluid motor means applies a regulated andsubstantially constant force and the wrench thereby applies anaccurately regulated torque, all independently of other restraints onthe frame or on the workpiece, the applied torque being determined andlimited by the applied fluid pressure, and there being no freedom ofmovement of any portion of the driver element from the fastener elementwhen they are engaged which would enable a differential velocity toUNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Patent No. 3 ,868,872 Dated March 4, 1975 Q In e fl GEORGE S. WING It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below: Col. 1, line 51 "pre-load,should read --"preload",--

Col. 2, line 7 "extend" should read "extent-- Col. 2, line 47 'Means,should read --Means",

Col. 5, line 55 "he" should read --the-- Col. 6, line 44 "chamber"should read --chambers-- G C010 6, line 46 "branches respective" shouldread --respective branches-- C010 8 line 28 insert a comma between "167"and Q Col. 9, line 11 "ad-justing" should read --adjusting-- Col. 9,line 23 "device" should read --devices-- Col. 10, line 37"counter-clockwise" should read "counterclockwise-- 0* Col. 11, line60-61 "provided" should read -providing-- ((101. 14, line 3 "arms"should read --arm-- Cl. 2, line 26) Signed and Scaled this Sixth Day ofJuly 1976 [SEAL] Arrest: O

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufParenlxand Trademarks

1. An internally reacting system for attaching one of its elements toanother of its elements at a predetermined torque level and with apredetermined level of axial tensile preload, said system comprising adriver element, a fastener element having an axis, a workpiece element,and an interlinking element for interlinking the driver element and theworkpiece element, said fastener element comprising a pin with acylindrical shank having a central axis, a peripheral thread on saidshank, and a collar including a peripheral flange, a peripheral bearingface on said peripheral flange, an axially-extending nose projectingbeyond said bearing face bearing an outer wall, and an internal thread,said collar being adapted to be threaded and tightened onto theperipheral thread of the pin, said workpiece comprising a body having abounding surface and an aperture opening onto said bounding surface intowhich the shank fits, the peripheral thread projecting beyond saidbounding surface, the pin being restrained against axial removal fromthe workpiece in the direction of the peripheral thread, saidinterlinking element comprising a washer including engagement surfaces,a central aperture at least in part defined by an inner wall to encircleand to pass the pin, and bearing surfaces to abut against the collar andagainst the workpiece when clamped between them by tightening the collaronto the pin, and the washer being restrained against rotation relativeto the workpiece at least in part by frictional forces developed fromcompressive forces on the bearing surfaces, which forces are exerted onthe washer by the collar through the said peripheral bearing facedisposed on the said peripheral flange, the axially-projecting nose ofthe collar being adapted to be inserted into the central aperture of thewasher, its outer wall having lateral dimensions such that when soinserted they are less than corresponding lateral dimensions of theinner wall, whereby the nose is radially spaced from the inner wall ofthe central aperture when the fastener element is fully assembled, atleast the first three completely formed thread convolutions of thecollar closest to the end of the nose most removed from the peripheralflanges lying axially within the nose, whereby to be located closer tothe workpiece than the bearing face on the collar, said driver elementcomprising a frame, engagement means on said frame to engage theengagement surfaces on the interlinking element and restrain the frameagainst rotation relative thereto, a wrench having a central axis ofrotation rotatably mounted to the frame and adapted to engage the collarto tighten it onto the peripheral thread, a lever arm attached to thewrench, projecting therefrom and adapted to be driven in an arc aroundthe said central axis to turn the wrench, fluid motor means mounted tothe frame and connected to the lever aRm at a distance from the centralaxis to cause said driving of the lever arm, a source ofpressureregulated fluid, and valve means admitting said fluid to thefluid motor under pressure so as to drive the same with a predeterminedforce against the lever arm of predetermined length, whereby theinterlinking means restrains the frame against rotation while the wrenchtightens the collar onto the pin, and the fluid motor means applies aregulated and substantially constant force and the wrench therebyapplies an accurately regulated torque, all independently of otherrestraints on the frame or on the workpiece, the applied torque beingdetermined and limited by the applied fluid pressure, and there being nofreedom of movement of any portion of the driver element from thefastener element when they are engaged which would enable a differentialvelocity to exist.
 2. An internally reacting system for attaching one ofits elements to another of its elements at a predetermined torque leveland with a predetermined level of axial tensile pre-load, said systemcomprising a driver element, a fastener element, a workpiece element,and an interlinking element for interlinking the driver element and theworkpiece element, said fastener element comprising a pin with acylindrical shank, a peripheral thread on said shank, and an internallythreaded collar adapted to be threaded and tightened onto the peripheralthread, said workpiece comprising a body having a bounding surface andan aperture opening onto said bounding surface into which the shankfits, the peripheral thread projecting beyond said bounding surface, thepin being restrained against axial removal from the workpiece in thedirection of the peripheral thread, said interlinking element comprisinga body with engagement surfaces, said body being adapted to berestrained against rotation relative to the workpiece, said driverelement comprising a frame, engagement means on said frame to engage theengagement surfaces on the interlinking element and restrain the frameagainst rotation relative thereto, a drive shaft mounted to said frameand rotatable therein around a central axis; a lever arm;unidirectionally driving clutch means engaging the lever arms to thedrive shaft for driving the drive shaft in one direction of lever motionand releasing it in the other direction; a bi-directional fluid motormounted to said frame and drivingly connected to said lever arm, saidfluid motor having a pair of supply ports; pressure conduit means;exhaust conduit means; an adjustable pressure regulator in said pressureconduit means maintaining pressure downstream therefrom at a constantand selected value; direction selector valve means in said pressureconduit downstream from said regulator; a pair of supply conduitsconnected to said direction selector valve means, one being connected toeach supply port of the fluid motor; pilot means contactible by thelever arm and operatively connected to said direction selector valvemeans for setting the same and thereby determining the direction ofoperation of the fluid motor, the fluid motor thereby cyclingbi-directionally and driving the lever arm back and forth and drivingthe drive shaft unidirectionally as a consequence of the alternateengagement and release of the clutch means, said valve means admittingfluid to the fluid motor under pressure so as to drive the same with apredetermined force against the lever arm, whereby the interlinkingmeans restrains the frame against rotation while the wrench tightens thecollar onto the pin, and the fluid motor means applies a regulated andsubstantially constant force and the wrench thereby applies anaccurately regulated torque, all independently of other restraints onthe frame or on the workpiece, the applied torque being determined andlimited by the applied fluid pressure, and there being no freedom ofmovement of any portion of the driver element from the fastener elementwhen they are engaged which would enable a differential velocity toexist.